So named because of the black or green horn on its bottom end, the tomato hornworm is large and green with white bars on its sides. It leaves droppings and large holes on the leaves and fruit of the tomato plant, and it will defoliate your tomato garden if left unchecked. The best defense against the tomato hornworm is offense. Here are a few ways to keep these critters in check and keep your garden green.
Get down on your hands and knees and look underneath your tomato plants for evidence of horn worms. Green droppings are usually the best indicator. If you see any horn worms or larvae on your tomato plants, remove them by hand.
Make a hot pepper or soap and lime spray and spray it directly onto the worms. To make the spray, chop ½ cup of hot peppers, and mix them with 2 cups of hot water. Strain and spray. The capsaicin in the peppers should cause nerve damage to the insects and repel them from the plants.
Do things to invite birds to the garden. Build birdhouses, put out bird feeders and bird baths. They are natural predators to the tomato hornworms.
Use bug zappers if other means of control haven’t worked, but use them sparingly, as they also kill beneficial insects such as wasps and bees.
Cultivate your garden completely in the fall by exposing the soil down to two inches and allowing the birds to access any worms on the surface. After two days, rake the soil again to expose anymore that may have hatched, and after another day or two, plant a cover crop or mulch heavily.
Plant ally crops such as dill, opal basil and marigolds nearby.
Use biological controls such as ladybugs, wasps and lacewings to attack the eggs of hornworms.
Use a botanical control, such as 1-percent solution of Rotenone.